The present invention relates to an electric staple in which a magazine in unmovably fixed to a body frame so that a driver for driving out a staple is rectilinearly moved.
There is a type of an electric stapler in which a magazine is pivotally coupled to a body frame so as to be swingable, as disclosed in the Japanese Patent examined Publications Nos. 26825/89 and 25670/89. Since a driver is swung together with the magazine, the driver is moved along an arc relative to a clincher so that the direction of driving-out of a staple is not coincident with the center line of the clincher. For that reason, a stapling failure or the like is likely to occur, and high motive power is needed for swinging the magazine. This is a problem.
There is another type of an electric stapler in which a magazine is unmovably fixed to a body frame, as disclosed in the Japanese Patent Examined Publication No. 18201/90. The distance between the staple drive-out opening of the magazine and a clincher is fixed. As a result, if the thickness of a stapled material is small, the distance between the opening and the stapled material is so large that a staple driven out of the magazine is not supported at the legs of the staple until the points of the legs reach the material. For that reason, the staple is likely to tilt to undergo buckling resulting in a stapling failure. This is a problem.
There is yet another type of an electric stapler in which the swing of a clincher is synchronized with that of a magazine by a mechanism so that the drive out opening of a magazine and the clincher are always kept on an imaginary line, as disclosed in the Japan Utility Model Application (OPI) Nos. 23374/89 and 84981/89 (the term "OPI" as used herein means an "unexamined published application"). Since the magazine and a staple driver are moved together at the time of driving out a staple, a means by which staples in a cartridge are held not to sway at the time of the swing of the magazine needs to be provided if the cartridge is disposed on the magazine. This is a problem.
A first aspect of the present invention was made in order to solve the problems mentioned above. Accordingly, it is an object of the invention to provide an electric stapler of the magazine unmovable fixation type, which does not need high motive power and operates so that the legs of a staple are quickly supported after the driving-out thereof to prevent the staple from undergoing wrong clinching such as buckling, and wherein a staple sheet does not sway in a cartridge.
The present device of a second aspect of the present invention relates to a staple sheet feeder which is for an electric stapler which functions so that staple sheets stacked together in a cartridge are sequentially moved therefrom and fed to the prescribed position.
As for a conventional electric stapler of the type in which the straight staples of a staple sheet consisting of the straight staples conjoined together are sequentially formed as U and then driven out of the stapler, starting with the foremost of the staples, the staple sheet needs to be fed from a prescribed position to the forming and drive-out portion of the stapler. For such feeding, a number of feeders were developed as disclosed in the Japan Patent Application (OPI) Nos. 79977/87 and 120086/88 (the term "OPI" as used herein means an "unexamined published application").
In one of the feeders, a feed claw is engaged with a staple sheet and swung so that staples are fed sequentially. Since the length of the feed of the staple sheet by the feed mechanism of the feeder needs to be set to correspond to the size of a single staple, the processed components of the feeder and the assembly and maintenance of the components are required to be accurate. This is a problem.
In another of the feeders, a staple sheet is continuously fed by an endless belt as described in the Japanese Patent Applications (OPI) Nos. 76312/86 and 255080/87. Since the feeder does not have a means for modulating the frictional force between the endless belt and the staple sheet in a cartridge, it is necessary to adjust both the cartridge housing portion of a magazine and the component of an endless belt running means to each other in their assembly so as to present an optimal frictional force between the endless belt and the staple sheet. This is a problem. There is another problem in that the endless belt is likely to be relatively much worn.
The present device of the second aspect of the present invention was made in order to solve the problem mentioned above. Accordingly, it is an object of the invention to provide a staple sheet feeder which is for an electric stapler and by which a staple sheet can be smoothly and securely fed without using an accurate component and performing the adjustment thereof in assembly.
The present device of a third aspect of the present invention relates to a staple sheet detector which is for an electric stapler housing staple sheets stacked together in a cartridge so as to be sequentially moved out of the cartridge and fed to the front of magazine and finds out whether the staple sheets are already all moved out of the cartridge.
As for a conventional electric stapler of the type in which a staple sheet consisting of straight staples conjoined together is formed as U at each staple and the staple is then driven out from the stapler, the staple sheets are stacked together in a cartridge and the cartridge is then fitted to a magazine. After the staple is moved out of the fitted cartridge to the forming front portion of the magazine by a feeder, the foremost staple of the sheet is formed as U and then driven out into a stapled material. To prevent the stapler from performing such staple driving-out operation without the staple, a staple sheet detector for finding out whether the staple sheet is in the cartridge or not, as disclosed in the Japan Utility Model Application (OPI) No. 112873/86 (the term "OPI" as used herein means an "unexamined published application"). The staple sheet detector is made of a reflection-type photosensor provided in such a position as to face the lowermost staple sheet. The fact that light for the photosensor is not reflected by the staple sheet if the sheet is not in the cartridge is utilized for the staple sheet detector to find out whether there is a staple sheet in the cartridge. However, the photosensor is expensive, and the reflectance of the surface of the staple sheet is nonuniform to make the photosensor likely to operate wrongly This is a problem.
The present device of the third aspect of the present invention was made in order to solve the problem mentioned above. Accordingly, it is an object of the device to provide a staple sheet detector for finding out whether there is a stable sheet in a cartridge in an electric stapler.
The present device of a fourth aspect of the present invention relates to a mechanism for fixing a stable sheet housing cartridge to an electric stapler of the type in which a staple sheet is partly bent as U and a staple is then driven out.
Arts, in each of which a cartridge of such kind is fitted to the magazine of an electric stapler, were disclosed in the Japan Patent Application (OPI) No. 255082/87 and the Japan Utility Model Applications (OPI) Nos. 38982/88, 60880/89, 74076/89 and 87330/89 (the term "OPI" as used herein means an "unexamined published application"). In the stapler, staple sheets in the cartridge are sequentially fed out of it, starting with the lowermost of the staple sheets, by a feed belt provided under the cartridge, and the staple sheet housing body of the cartridge is vertically pushed toward the top of the feed belt to increase the frictional force between the lowermost staple sheet and the top of the feed belt to surely move the staple sheets one after another out of the housing body. For that reason, a force for fixing the housing body of the cartridge is made stronger than a force for fixing the front end part of the cartridge. As a result, the fixation of the front end part of the cartridge is likely to become unstable due to the vibration of the stapler in operation so that the vertical dimension of a staple sheet passage is changeable. Consequently, the foremost staple 340a of the staple sheet 340 is likely to turn by an angle of 90 degrees in such a direction that the load on the electric motor of the staple in bending the staple as U on an anvil 341 with a forming plate 342 by the power of the motor as shown in FIG. 17 is increased. This is a problem.
The present device of the fourth aspect of the present invention was made in order to solve the problem mentioned above. Accordingly, it is an object of the device to provide a mechanism for firmly fixing a cartridge to the cartridge fitting portion of an electric stapler so that the cartridge is not displaced relative to the portion due to the vibration of the stapler in operation.
The present device of a fifth aspect of the present invention relates to a staple sheet housing cartridge for an electric stapler of the type in which a staple sheet is bent to be formed as U and a staple is then driven out.
A conventional cartridge of such kind has a projection on the bottom of the front guide portion of the cartridge at the center of the bottom so that the projection pushes a staple sheet onto an endless belt which is a feed means, as disclosed in the Japanese Utility Model examined Publication No. 34855/88. The endless belt is tightly disposed to extend from the staple sheet housing body of the cartridge to the front end of the guide portion. Since the belt is pushed by the projection of the guide portion through the staple sheet, the distance between the belt and the sheet is decreased throughout a prescribed length to increase the frictional force between the sheet and the belt throughout the length so that deforming load does not concentrate on the sheet. For that reason, the staple of the sheet is not separated from the other staple thereof.
However, as for a cartridge having a feed roller means instead of such an endless belt and having a projection on the guide portion of the cartridge, a staple sheet receives load only at the place where the roller of the feed roller means is opposed to the projection. For that reason, the staple sheet is likely to be broken into parts. This is a problem.
The present device of the fifth aspect of the present invention was made in order to solve the problem mentioned above. Accordingly, it is an object of the device to provide a cartridge optimal for an electric stapler having a feed roller means.
The present device of a sixth aspect of the present invention relates to a staple sheet housing cartridge for an electric stapler of the type in which a staple sheet is partly bent as U and a staple is then driven out.
Generally, a cartridge of such kind housed staple sheets each consisting of staples conjoined together, so that the staple sheets are stacked together in the cartridge. The cartridge is fitted to the magazine of an electric stapler. The lowermost of the staple sheets is moved forward out of the housing body of the fitted cartridge through an outlet port provided at the bottom of the front wall of the housing body, and the staple is then bent as U and driven out. As described in a Japanese Utility Model Examined Publication No. 34854/88, a pusher is provided in the cartridge to push the entire housed staple sheets downward to make the feeding of the lowermost staple sheet good. Since the pusher has a pressure spring provided at the center of the cartridge, the entire staple sheets therein are pushed downward. For that reason, if the lowermost staple sheet is warped as a whole so as to have its central portion located below both the ends of the sheet, the front end of the sheet is likely to be caught at the outlet port so that the sheet is not smoothly moved out of the housing body through the outlet port. If a feed means provided at the magazine of the electric stapler to move the lowermost staple sheet forward out of the cartridge is made of a roller, the roller needs to be disposed near the front of the bottom of the cartridge because the area of the contact of the roller and the sheet is very small. The position of the pusher needs to correspond to that of the roller.
The present device of the sixth aspect of the present invention was made in order to solve the problem mentioned above. Accordingly, it is an object of the present device to provide a cartridge which is optimal for an electric stapler having a feed means made of rollers and makes it possible to securely and smoothly move a staple sheet out of the cartridge.